Remove resource_component_transfer and resource_merge event types

For transfer and merging type events, there were at least two
different types of events: resource_component_transfer and
resource_merge. After thinking it over and seeing my request
for a 'component_transfer' event type, I figured that it was
best to treat merges and components the same in terms of the
events that got created. The following workflows should all
ultimately have events created with type 'component_transfer':

* Merging two resources into one
* Merging two digital objects into one
* Transferring components from one resource to another
* Transferring components from one digital object ot another